#ifndef __Skygen_TilingPerlinNoise_h__
#define __Skygen_TilingPerlinNoise_h__

namespace Orca {

	template<typename real>
	class TTilingPerlinNoise {

	public:
		TTilingPerlinNoise(int tilingSize)
			: mTilingSize(tilingSize) {

			int permutation[] = { 
				151,160,137,91,90,15,
				131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,
				21,10,23,190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,
				35,11,32,57,177,33,88,237,149,56,87,174,20,125,136,171,168, 68,175,
				74,165,71,134,139,48,27,166,77,146,158,231,83,111,229,122,60,211,133,
				230,220,105,92,41,55,46,245,40,244,102,143,54, 65,25,63,161, 1,216,
				80,73,209,76,132,187,208, 89,18,169,200,196,135,130,116,188,159,86,
				164,100,109,198,173,186, 3,64,52,217,226,250,124,123,5,202,38,147,
				118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,223,
				183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,
				172,9,129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,
				218,246,97,228,251,34,242,193,238,210,144,12,191,179,162,241, 81,51,
				145,235,249,14,239,107,49,192,214,31,181,199,106,157,184, 84,204,176,
				115,121,50,45,127, 4,150,254,138,236,205,93,222,114,67,29,24,72,243,
				141,128,195,78,66,215,61,156,180
				};

			for(int i = 0; i < 256; i++) 
				p[256+i] = p[i] = permutation[i]; 

			int grad3[12][3] = {
				{1,1,0},{-1,1,0},{1,-1,0},{-1,-1,0},
				{1,0,1},{-1,0,1},{1,0,-1},{-1,0,-1},
				{0,1,1},{0,-1,1},{0,1,-1},{0,-1,-1}
			};

			for(int i = 0; i < 12; ++i) {
				g[i][0] = grad3[i][0];
				g[i][1] = grad3[i][1];
				g[i][2] = grad3[i][2];
			}
		}

		real pnoise(real x, real y, real z) {

			int	X = (int)floor(x) % mTilingSize,
				Y = (int)floor(y) % mTilingSize,
				Z = (int)floor(z) % mTilingSize;

			int X_ = (X + 1) % mTilingSize;
			int Y_ = (Y + 1) % mTilingSize;
			int Z_ = (Z + 1) % mTilingSize;

			x -= floor(x);														// FIND RELATIVE X,Y,Z
			y -= floor(y);														// OF POINT IN CUBE.
			z -= floor(z);

			int gi000 = _perm(X  + _perm(Y  + _perm(Z ))) % 12;
			int gi001 = _perm(X  + _perm(Y  + _perm(Z_))) % 12;
			int gi010 = _perm(X  + _perm(Y_ + _perm(Z ))) % 12;
			int gi011 = _perm(X  + _perm(Y_ + _perm(Z_))) % 12;
			int gi100 = _perm(X_ + _perm(Y  + _perm(Z ))) % 12;
			int gi101 = _perm(X_ + _perm(Y  + _perm(Z_))) % 12;
			int gi110 = _perm(X_ + _perm(Y_ + _perm(Z ))) % 12;
			int gi111 = _perm(X_ + _perm(Y_ + _perm(Z_))) % 12;

			real n000 = _dot(g[gi000], x  , y  , z);
			real n100 = _dot(g[gi100], x-1, y  , z);
			real n010 = _dot(g[gi010], x  , y-1, z);
			real n110 = _dot(g[gi110], x-1, y-1, z);
			real n001 = _dot(g[gi001], x  , y  , z-1);
			real n101 = _dot(g[gi101], x-1, y  , z-1);
			real n011 = _dot(g[gi011], x  , y-1, z-1);
			real n111 = _dot(g[gi111], x-1, y-1, z-1);
			
			real u = _fade(x),													// COMPUTE FADE CURVES
				 v = _fade(y),													// FOR EACH OF X,Y,Z.
				 w = _fade(z);

			real nx00 = _lerp(n000, n100, u);
			real nx01 = _lerp(n001, n101, u);
			real nx10 = _lerp(n010, n110, u);
			real nx11 = _lerp(n011, n111, u);

			// Interpolate the four results along y
			real nxy0 = _lerp(nx00, nx10, v);
			real nxy1 = _lerp(nx01, nx11, v);

			// Interpolate the two last results along z
			return _lerp(nxy0, nxy1, w);
		}
		
	private:
		int p[512];
		int g[12][3];
		int mTilingSize;
		
		inline real _fade(real t) {
			return t * t * t * (t * (t * 6 - 15) + 10);
		}

		inline real _lerp(real a, real b, real t) {
			return a + t * (b - a);
		}

		inline real _dot(int g[], real x, real y, real z) {
			return g[0]*x + g[1]*y + g[2]*z;
		}

		inline int _perm(int x) {
			return p[x];
		}
};
}

#endif	// __Skygen_TilingPerlinNoise_h__